The present invention relates generally to the infusion of a substance, in particular drugs, into a patient's body and, more specifically, to the stimulation of penis erection.
When a male is stimulated erotically, connections between arteries and veins are closed (arteriovenous anastomoses) so that blood which is normally able to bypass the empty spaces or sinuses of the corpora cavernosa is retained in the penis.
The main vessels supplying the blood to the cavernous spaces in the erectile tissue of the corpora cavernosa are the deep arteries of the penis. They are therefore heavily involved in the erection of the penis. They give off numerous branches—the helicine arteries—that open directly into the cavernous spaces. When the penis is flaccid, these arteries are coiled, restricting blood flow. However, the smooth muscle in the coiled helicine arteries relaxes as a result of parasympathetic stimulation. In their relaxed state, the helicine arteries straighten, enlarging their lumina and allowing blood to flow into and dilate the cavernous spaces in the corpora of the penis at arterial pressure. In combination with the bulbospongiosus and ischiocavernosus muscles compressing the veins egressing from the corpora cavernosa, the erectile bodies of the penis become enlarged and rigid, and an erection occurs.
Patients suffering from erectile dysfunction can cause the penis to become turgid by injecting into the corpora cavernosa a medicament, such as papaverine or prostaglandin E1, causing the smooth muscles to relax. The patients have to learn a certain technique under doctor's supervision in order to be able to properly inject the medicament in each of the corpora cavernosa. Only after about 15 minutes after administration of the medicament will the medicament become effective. Furthermore, the available medicaments are only stable as a dry substance (and typically cooled). Consequently, since long term storage of drugs stimulating penis erection is not possible with many currently available drugs, the drug to be injected would typically be provided as a first substance, such as a saline solution, to be mixed with a second, dry substance for injection shortly before the injection is performed. Thus, the entire procedure is inconvenient for the patient, the more so as proper administration and dosing is critical since the medicament may be transported with the blood into other regions of the patient's body if the injection is not done properly.
Recently, a different method has become known under the brand Muse®. In this method, a plastic rod comprising the medicament alprostadil is inserted into the urethra. Upon pressing a button, the alprostadil is released from the rod into the urethra. After removal of the plastic rod, the penis is rolled between the palms of the hands so that the medicament dissolves, distributes and is absorbed through the urethra wall. However, proper dosage and administration is also critical in this method.
The afore-mentioned problems are not limited to the administration of drugs stimulating penis erection. Similar problems can also occur in other applications where long term storage of a drug to be injected is difficult and, therefore, the drug must be kept cool and mixed together with other substances shortly before administering it to the patient.
It is therefore the object of the present invention to improve the administration of a drug into a patient's body, and more specifically to improve the stimulation of penis erection, so that the entire process is more reliable and more convenient for the patient.